The present invention relates to field of Intraocular Lenses (IOLs). In particular, the present invention relates to Intraocular Lenses wherein an electro-active element provides at least a portion of the IOL's refractive power, or prismatic power, or at least a portion of the tinting.
Intraocular lenses (IOLs) are typically permanent, plastic lenses that are surgically implanted inside of the eyeball to replace or supplement the eye's natural crystalline lens. They have been used in the United States since the late 1960s to restore vision to cataract patients, and more recently are being used in several types of refractive eye surgery.
The natural crystalline lens is critical component of the complex optical system of the eye. The crystalline lens provides about 17 diopters of the total 60 diopters of the refractive power of a healthy eye. Further, a healthy crystalline lens provides adjustable focusing when deformed by the muscular ciliary body that circumferentially surrounds the crystalline lens. As the eye ages, the flexibility of the crystalline lens decreases and this adjustable focusing is diminished. Thus, this critical crystalline lens almost invariably loses flexibility with age, and often loses transparency with age due to cataracts or other diseases.
Most intraocular lenses used in cataract surgery may be folded and inserted through the same tiny opening that was used to remove the natural crystalline lens. Once in the eye, the lens may unfold to its full size. The opening in the eye is so small that it heals itself quickly without stitches. The intraocular lenses may be made of inert materials that do not trigger rejection responses by the body.
In most cases, IOLs are permanent. They rarely need replacement, except in the instances where the measurements of the eye prior to surgery have not accurately determined the required focusing power of the IOL. Also, the surgery itself may change the optical characteristics of the eye. In most cases, the intraocular lenses implanted during cataract surgery are monofocal lenses, and the optical power of the IOL is selected such that the power of the eye is set for distance vision. Therefore, in most cases the patient will still require reading glasses after surgery. Intraocular lens implants may be static multifocal lenses, which attempt to function more like the eye's natural lens by providing clear vision at a distance and reasonable focus for a range of near distances, for patients with presbyopia. Not all patients are good candidates for the multifocal lens; however, those who can use the lens are some what pleased with the results.
More recently, accommodative IOLs have been introduced. These accommodative IOLs actually change focus by movement (physically deforming and/or translating within the orbit of the eye) as the muscular ciliary body reacts to an accommodative stimulus from the brain, similar to the way the natural crystalline lens focuses. While these offer promise, accommodative IOLs still have not been perfected. In spite of these limited successes, the multi-focal IOL and present accommodative IOLs still have a substantial decrease in performance when compared to a healthy natural crystalline lens.
Another ocular lens that holds promise for correcting presbyopia is the Small Diameter Corneal Inlay (SDCI). The Small Diameter Corneal Inlay (SDCI) is a prescription lens that is inserted into the corneal tissue to create an effect similar to a bifocal contact lens. Corneal Inlays (SDCI) are early in their development and it is still too early to understand how well they will function and also how effective they will become.
While all these emerging surgical procedures have their merits, they all have a substantial decrease in performance when compared to a young healthy natural crystalline lens. The present invention addresses these shortcomings by providing an intraocular lens that behaves in a manner similar to the natural crystalline lens.